No-Frills imaging refers to the use of basic photographic equipment either in conjunction with a telescope (afocal photography), or with a camera and triipod on it's own.
Let's see what we can do with a camera, tripod, lens and cable/remote release.
Widefield imaging
This can be a good way to photograph star fields (the Milky Way for example) and larger nebulae (M31 or M42 for example). All you need for this is a camera, a suitable lens, a sturdy and stable tripod, and a cable or remote release for the shutter.
A few basics
Depending on the size of the field of view you wish to photograph, you'll need a suitable lens. For something like the Moon, a long zoom is ideal, for capturing a constellation like Orion, you'll need a shorter wide angle lens. In either case, the faster the lens (lower f number) the better. If you're capturing dim objects like stars then you'll need a long exposure time but you also need to take the rotation of the Earth into account - too long an exposure will cause the stars to blur and start to trail.
The 500 rule.
To avoid star trailing and to get sharp long exposure images of the night sky, there's a simple rule to follow which states that the maximum exposure time you can have before your stars begin to blur is 500 divided by the focal length of the lens you're using as a 35mm camera equivalent.
What does 35mm camera equivalent mean?
The film frame size on a 35mm camera is 36x24mm but the majority of digital sensors use a smaller or crop sensor which means a correction has to be made for this. For Canon cameras, the crop factor is 1.6. For Nikons, it's 1.5, for 4/3 cameras, it's 2
So for my Canon camera using a 20mm lens, my maximum exposure time would be 500 / (20 x 1.6) or 500 / 32 = 15.6 seconds
The same camera using a 500mm lens would give 500 / (500 x 1.6) or 500 / 800 = 0.6 seconds
So to avoid blurring or trailing with my 20mm lens, I'd need to keep the exposure below 15 seconds, and for the 500mm lens, below half a second.
Exposure times
Because stars are relatively faint objects, long exposures are needed in order to capture as much light from them as possible. If you're taking photographs of star fields, nebulae or other faint objects then a moonless night really is a must. Using a fixed tripod means that the exposure time is limited by the Earth's rotation (15 degrees per hour) if sharp images are required. The amount of light captured can be increased two methods other than shutter speed. The first by using a fast lens at maximum aperture, the second is by increasing the sensitivity of the sensor (it's actually increasing the amplification but we'll keep this simple) by increasing the ISO speed. However, increasing the sensitivity also means increasing the amount of random noise in the image and there's a point where the amount of noise degrades the image too much. It's different for every camera and you should become familiar with your own by pushing the ISO up to see where the maximum acceptable degradation is.
Focusing
Switch all automatic focusing systems off and focus manually. Most lenses will have a focus ring and markings to indicate distance. Set the lens to infiinity or if there are no markings, you can focus on the moon if that's up.
Star trails
Start trails can be fascinating images, they're quite simple to make but there are a few basic rules that you'll need to follow. You might think it's a simple process of point the camera and leave the shutter open for a long time but that's not really practical for several reasons. Firstly even the lowest light conditions are going to overexpose and produce excessive noise with very long exposures, secondly the Earth rotates at a realtively slow 15 degrees per hour - to get long trails is clearly going to take many hours of patient image makiing. The best method by far is to take many images at regular intervals and then use software to combine or stack the images together.
You'll need to find a dark site with no nearby roads or other bright liight sources. Foreground features will give the final image a sense of composition but these obviously need to be stationary. Think about what you want your final image to look like. If you want circular trails then you'll have to make sure that Polaris is roughly in the centre of your image, for star arcs, this is not necessary. A sturdy and stable tripod is needed and for most images, a wide angle lens is used. You'll need a cable or remote release and one with a built in intervalometer is ideal - this will automate the process and leave you time to enjoy the surroundings and sky.
You should be aiming to take a number of images at regular intervals. 50-60 images taken at minute intervals with an exposure time of 40-45 seconds will give you good results.
I recommend shooting your images in RAW rather than Jpeg as this will allow you more control over the final image and allow good white balance correction. The drawback to this is that you'll have to process all of the images before you stack them but the end result should make it worth the effort.
Exposure is not an exact science. It depends on the camera and lens, the ISO setting and aperture setting. I recommend some bracketed test shots to assess the exposure. Aim for a lower ISO than the single shot widefield images described above to keep noise to a minimum. ISO 800 is a good starting point with an aperture of f2.8-f5.6 and an exposure time of 40-45 seconds. Depending on the stacking software you decide to use, you can shoot some frames with the lens cap on to provide 'dark' frames for noise reduction.
The stacking software I recommend is Markus Enzweiler's StarStax. It's freeware and is available for Windows, OS X and Linux.
Afocal imaging
This is perhaps the simplest of all the imaging techniques. No tripod is needed just your telescope and a camera.
This is obvious when you think about it. You look through a telescope eyepiece to see the object you're observing so why not replace your eye with a camera? That's it. Afocal imaging in a nutshell. Special adaptors are available commercially to hold your camera in alignment with the eyepiece (and at higher magnifications getting the light paths matched can be tricky so this will help). Exposure can be automatic for bright objects like the moon or planets, or 'B' for dim objects.